1. Field of the Invention
The present invention relates to the field of mass spectrometry, and more particularly to a mass spectrometer multipole device that enables the merging of ion beams from separate sources and/or for directing a single ion beam into a plurality of directions for collection and/or analysis.
2. Discussion of the Related Art
Mass spectrometry is an analytical technique that enables the identification of chemical compositions of a sample based on the mass-to-charge ratio of charged particles. Generally, analytes in a sample are ionized and thereafter separated via their mass wherein the ratio of a respective charge to mass is determined by passing them through electric and magnetic fields so as to result in a desired mass spectrum.
In particular, the design of a mass spectrometer to enable separation and detection most often includes: an ion source to transform introduced molecules in a sample into ionized particles; an analyzer to separate such ionized particles by their masses by applying electric and magnetic fields; and a detector to measure and thus provide data for calculating the abundances of each ion present.
As known to those skilled in the art, in the design of such a spectrometer system, the ionized particles resulting from the ion source are often directed along an ion path using ion steering optics, such as, but not limited to cylindrical lenses, einzel structures, skimmers, and multipole rod configurations, etc. In the multipole rod configuration, the number of rods can be any even number, such as four, six, or eight with high-frequency voltages having inverted phases applied to electrodes adjacent to each and often in electrical cooperation with additionally applied direct current (DC) voltages. Accordingly, ions introduced along a longitudinal direction into such structures proceed by oscillation in a predetermined cycle due to a high frequency electric field caused by the aforementioned voltages so as to direct a desired amount of ions to a subsequent stage.
While such ion steering optics, and in particular, the mutipole rod configurations, beneficially enable the desired ions to be directed along predetermined paths, such designs do not provide for the merging of ion beams from two distinct sources, or for redirecting a single ion beam in one direction or another as disclosed by the novel and beneficial configurations of the present invention.
To give the reader an idea of the technical capabilities presently in the field, one can look to background information for a system that uses movably mounted multipoles to couple one or more ion sources to a mass spectrometer, which is described and claimed in U.S. Pat. No. 5,825,026, entitled “Introduction of Ions from Ion sources Into Mass Spectrometers,” issued Oct. 20, 1998, to Baykut, including the following, “The basic idea of the invention is to movably position one or several curved multipole ion guides, so that in a system of multiple stationary ion sources, each source can be used one after another by adjusting the movable multipole. The ions originating from various ion sources, which however are directed toward a common point, can be introduced into the mass spectrometer, using a rotatable multipole ion guide arrangement. The ions can be transferred directly into an rf ion trap or into a quadrupole or sector mass spectrometer, or also an ion transfer line of a FTICR spectrometer. For this purpose, a multipole (e.g. a hexapole or octopole) is positioned adjustably around the axis of the ion trap or around of the axis of the ion transfer path of the FTICR mass spectrometer. The curved longitudinal axis of the multipole on the mass spectrometer side (injection side) is identical to the rotation axis of the rotatably positioned multipole. During a rotation, the other end of the multipole moves in a circle passing various ion sources. The rotation position of the multipole determines from which ion source the ions are transferred into the mass spectrometer.”
Moreover, background information for a system that utilizes a deflecting means to steer ions produced from a plurality of ion sources to a mass spectrometer, is described and claimed in U.S. Pat. No. 6,596,989 B2, entitled, “Mass Analysis Method and Apparatus for Mass Analysis,” issued Jul. 22, 2003, to Kato, including the following, “A mass analysis system is capable of performing a plurality of measurements in parallel by mounting a plurality of ion sources onto one mass spectrometer and speedily switching the ion sources. The mass analysis apparatus comprises a plurality of ion sources; and a deflecting means for deflecting ions from at least one ion source among the plurality of ions sources so that the ions travel toward the mass spectrometer by producing an electric field.”
Background information for an ion funnel to merge ions is described and claimed in U.S. Pat. No. 6,979,816 B2, entitled, “Multi-Source Ion Funnel,” issued Dec. 27, 2005, to Tang et al., including the following, “A method for introducing ions generated in a region of relatively high pressure into a region of relatively low pressure by providing at least two electrospray ion sources, providing at least two capillary inlets configured to direct ions generated by the electrospray sources into and through each of the capillary inlets, providing at least two sets of primary elements having apertures, each set of elements having a receiving end and an emitting end, the primary sets of elements configured to receive a ions from the capillary inlets at the receiving ends, and providing a secondary set of elements having apertures having a receiving end and an emitting end, the secondary set of elements configured to receive said ions from the emitting end of the primary sets of elements and emit said ions from said emitting end of the secondary set of elements. The method may further include the step of providing at least one jet disturber positioned within at least one of the sets of primary elements, providing a voltage, such as a dc voltage, in the jet disturber, thereby adjusting the transmission of ions through at least one of the sets of primary elements.”
Background information on a branched device to alternatively direct ions is described and claimed in U.S. Pat. No. 7,420,161 B2, entitled “Branched Radio Frequency Multipole,” issued Sep. 2, 2008, to Kovtoun, including the following, “Systems and methods of the invention include a branched radio frequency multipole configured to act, for example, as an ion guide. The branched radio frequency multipole comprises multiple ion channels through which ions can be alternatively directed. The branched radio frequency multipole is configured to control which of the multiple ion channels ions are directed, through the application of appropriate potentials. Thus, ions can alternatively be directed down different ion channels without the use of a mechanical valve.”
Additional background information for a system that uses an electrical lens to merge ion beams, is described and claimed in U.S. Pat. No. 7,372,042 B2, entitled “Lens Device For Introducing A Second Ion Beam Into a Primary Ion Path,” issued May 13, 2008, to Mordehai et al., including the following, “The invention provides a device for introducing a second ion beam into the primary ion path of a mass spectrometry system. In general, the device contains an electrical lens having a primary ion passageway and a secondary ion passageway that merges with the primary ion passageway. In certain embodiments, the electrical lens contains a first part and a second part that, together, form the primary ion passageway. The first part of the lens may contain the secondary ion passageway. A device for delivering ions to a mass analyzer and a mass spectrometer system containing the subject electric lens are also provided. Also provided by the invention are methods for introducing a second ion beam into a primary ion path using the subject electric lens, and methods of sample analysis.”
Finally, background information for a system that interfaces one or more ion sources via multipole rod configurations, is described and claimed in U.S. Pat. No. 7,358,488 B2, entitled “Mass Spectrometer Multiple Device Interface For Parallel Configuration of Multiple Devices,” issued Apr. 15, 2008, to Chernushevich et al., including the following, “A multi-device interface for use in mass spectrometry for interfacing one or more ion sources to one or more downstream devices. The multi-device interface comprises three or more multipole rod sets configured as either an input rod set or an output rod set depending on potentials applied to the multipole rod sets. The multipole rod sets configured as an input rod set are connectable to the one or more ion sources for receiving generated ions therefrom and sending the ions to at least one multipole rod set configured as an output multipole rod set. The output multipole rod sets are connectable to a downstream device for sending the generated ions thereto. At least two of the multipole rod sets are configured as input rod sets or at least two of the multipole rod sets are configured as output rod sets.”
Accordingly, while the above described inventions have beneficial applications, a large customer need exists for a mass spectrometer system that utilizes multipole ion optics in a novel interlaced configuration, as disclosed herein, which can not only merge ion beams from two separate sources but can also be used to direct a single ion beam into a plurality of desired directions. The present invention is thus directed to such a need.